Streptococcus mutans is recognized as the etiologic agent responsible for dental caries, and research on this organism has been promoted in order to better understand ways in which caries can be decreased. We have constructed two different gene libraries of the S. mutans chromose, and the availability of these genes allow a comprehensive study of the biological, chemical, and genetic properties of S. mutans surface protein antigens. The overall goal of this research is to define the surface protein antigens of S. mutans and elucidate their role in adherence or aggregation and contribution to dental caries. The specific aims of this study are to: 1) Identify and characterize the specific protein surface antigens of S. mutans. 2) Assess the role of each of the proteins individually and in groups in adherence and/or aggregation. 3) Determine which protein, if any, is responsible for the observed cross reactivity with human heart tissue; and 4) Study the genetic organization and regulation of these surface proteins. The results from this research should facilitate the study of individual S. mutans surface protein antigens and identify those proteins involved in adherence and aggregation. Some of these proteins could serve as candidate antigens for a dental caries vaccine. Additionally, identification of any possible proteins responsible for human heart cross reactivity is an important consideration for the development of a safe caries vaccine. Finally, a genetic approach to the organization and regulation of S. mutans surface proteins can only enhance our understanding of the overall biology of these organisms.